GTU Information Technology (Semester 5)
Computer Oriented Statistical Methods
June 2015
Total marks: --
Total time: --
INSTRUCTIONS
(1) Assume appropriate data and state your reasons
(2) Marks are given to the right of every question
(3) Draw neat diagrams wherever necessary


1 (a) Discuss the types of errors in performing numerical calculations.
4 M
1 (b) Does bisection method always converge? Discuss the comparison of iterative methods .
5 M
1 (c) Discuss the merits and demerits of the moving average method.
5 M

2 (a) (1) Discuss the consequences of normalized floating point representation of numbers with a suitable example.
(2) Evaluate \[\left ( \dfrac{\Delta ^{2}}{E} \right )x^{3}\]
7 M
2 (b) Write an algorithm for cubic spline interpolation.
7 M
2 (c) Find the first, second and third derivative of the function, tabulated below, at x=1.5:
x 1.5 2.0 2.5 3.0 3.5 4.0
f(x) 3.375 7.000 13.625 24.000 38.875 59.000
7 M

3 (a) (1) Obtain the function whose first difference is 9x2+11x+5. Show that its third difference is 18.
(2) Find the first term of the series whose second and subsequent terms are 8, 3, 0, -1, 0 .
7 M
3 (b) State Budan's theorem. Solve x3-8x2+17x-10=0 by Graffe's method, squaring three times.
7 M
3 (c) (i) Find the value of log 3 from \[\int_{0}^{1}\limits \dfrac{x^{2}}{1+x^{3}}dx\] using Simpson's rule by dividing the range into four equal parts.
3 M
3 (c) (ii) Write an algorithm to solve a differential equation by Runge-Kutta Method.
4 M
3 (d) Using Taylor series method, solve \[\dfrac{dy}{dx}=x+y\].Starting from x=1,y=0 and carry to x=1.2 with h=0.1. Compute the final result with the value of the explicit solution.
7 M

4 (a) (i) Find the value of x corresponding to y=12 using inverse interpolation:
x 1.2 2.1 2.8 4.1 4.9 6.2
y 4.2 6.8 9.8 13.4 15.5 19.6
4 M
4 (a) (ii) Solve by Jacobi's iterative method:
2x-3y+20z=25, 3x+20y-z=18,20x+y-2z=17.
4 M
4 (b) By the method of least squares, fit a parabola to the following data; also Estimate y at x=6.
X 1 2 3 4 5
Y 5 12 26 60 97
6 M
4 (c) Define Chebyshev polynomial. Obtain Taylor series expansion of e-x in terms of x . Approximate it in terms of Chebyshev polynomials.
7 M
4 (d) Determine the value of y(0.4) using predictor corrector method given \[\dfrac{dy}{dx}=xy+y^{2}\];y(0)=1; use Taylor series to get the values of y(0.1),y(0.2),y(0.3) Take h=0.1.
7 M

5 (a) (i) The coefficient of correlation between two variables X and Y is 0.48. The covariance is 36. The variance of X is 16. Find the standard deviation of Y.
4 M
5 (a) (ii) From the following table calculate the coefficient of correlation by Karl Pearson's method
X 39 65 62 90 82 75 25 98 36 78
Y 47 53 58 86 62 68 60 91 51 84
4 M
5 (b) The sales of a company in million of rupees for the years 1994-2001 are given below:
Year 1994 1995 1996 1997 1998 1999 2000 2001
Sales 550 560 555 585 540 525 545 585

Find the linear trend equation. Estimate the sales for the year 1993. Find the slope of the straight line trend.
6 M
5 (c) (i) If the relation between two random variables x and y is 2x+3y=4, find the correlation coefficient between them.
5 M
5 (c) (ii) Compute the seasonal index for the following data assuming that there is no need to adjust the data for the trend:
Quarter 1990 1991 1992 1993 1994 1995
I 3.5 3.5 3.5 4 4.1 4.2
II 3.9 4.1 3.9 4.6 4.4 4.6
III 3.4 3.7 3.7 3.8 4.2 4.3
IV 3.6 4.8 4 4.5 4.5 4.7
4 M
5 (d) If the two lines of regression are
4x-5y+30=0 and 20x-9y-107=0 which of these line of regression of x on y, and y on x. Find rxy and σy when σx=3.
5 M



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